Infection following a total joint replacement is an unavoidable complication affecting about 1.5% of patients resulting in an estimated 3,000 cases per year in North America alone. Eradication of the infection and the joint reconstruction, preferably by reimplantation of another joint, is important to a successful outcome.
Basically, three methods have developed in dealing with this problem. The first is excision of the joint, whereby the use of the limb is severely compromised.
Secondly, there is a two-stage joint replacement revision. With this method, the existing hip replacement and all infected tissue is removed. Antibiotic loaded cement beads are placed in the femoral and acetabular cavities and left there for a period of six to twelve weeks until the infection has been eradicated. Once the infection has been removed, a new total hip replacement is implanted. The disadvantage of this method is that the patient does not have normal use of the limb during the interim period during which the infection is being treated. This situation is illustrated in FIG. 1 of the accompanying drawings, where a patient's pelvic girdle 10 and femur 12 are shown with antibiotic loaded cement beads 14 located in the femoral and acetabular cavities 16 and 18, respectively. Not only is the patient immobilized during this period but hospitalization is also necessary, resulting in high medical expenses.
The permanent prosthesis which is fitted after the infection has been removed is either cemented in position or it is applied without cementing by forming a press-fit with the femoral cavity. In the latter case, the stem of the femoral component is provided with a rough outer surface so that the bone can grow into the cavities on the surface to bind with the prosthesis. In the case of application of cement to the stem, the cement is compressed into the interstices of the femoral cavity to provide rigid fixation of the component.
The third method is a one-stage hip replacement by which a permanent prosthesis is fitted directly, without the intermediate step of the application of antibiotic loaded bone cement beads. In this application, the bone cement which is used to bond the permanent prosthesis in the femoral cavity contains an antibiotic. Thus, the permanent hip replacement is fitted directly after the existing hip replacement and infected tissue have been removed. The bone cement is applied to the stem of the prosthesis. The stem is then inserted into the femoral cavity for bonding in the cavity.
There is mounting scientific evidence that the two stage approach is more effective in eradicating the infection and achieving an effective end result. But despite the advantages of this method, the patient usually remains immobilized and hospitalized for a period of six to twelve weeks.
It is an object of the present invention to provide a method and apparatus for treating a hip joint infection which retains all the benefits of the two-stage joint replacement revision but which avoids the immobilization and lengthy hospitalization.